The SEO URLs will be in next build, which probably will be out today. Example of the new SEO URLs as follows.
/community/1-category-001/10-group-010
/community/1-category-001/10-group-010/notifications
/community/1-category-001/10-group-010/edit
/community/1-category-001/10-group-010/message
/community/1-category-001/10-group-010/join
In the above the menu-alias is community. No it's not possible to remove the category id or group id as category name and group name are not unique and there's no separate alias column to store generated aliases (such feature may come at a later time). See the below for GJ 3.1.0 progress.
forge.joomlapolis.com/projects/groupjive/issues?query_id=71